Table 1_Pyoverdine-induced iron dysregulation exacerbates vascular endothelial barrier dysfunction under hyperglycemic conditions.xlsx

Diabetic foot infection (DFI) remains a leading cause of morbidity and mortality in diabetic patients, with Pseudomonas aeruginosa serving as a predominant pathogen due to its arsenal of virulence factors. Among these, the siderophore pyoverdine (PVD) is critical for bacterial iron acquisition and pathogenesis; however, its direct impact on the vascular endothelial barrier—particularly under hyperglycemic conditions—remains poorly understood. In this study, we employed Human Umbilical Vein Endothelial Cells (HUVECs) as a model to systematically evaluate the effects of PVD and high glucose (HG) on endothelial integrity. Transcriptomic analysis (RNA-seq) revealed that PVD significantly reshaped the gene expression profile of HUVECs, characterized by a marked upregulation of iron homeostasis-related genes, such as TFRC, indicating a state of apparent intracellular iron deficiency. Functional enrichment analysis further highlighted alterations in the extracellular matrix (ECM) and pathways associated with barrier function. In vitro assays demonstrated that PVD exposure reduced cell viability, triggered reactive oxygen species (ROS) bursts, and induced a loss of mitochondrial membrane potential. Ultrastructural observations via transmission electron microscopy confirmed pathological changes, including mitochondrial swelling, cristae disorganization, and cytoplasmic vacuolation. Functional assessments showed that PVD significantly increased the transendothelial flux of FITC-dextran and downregulated the expression of the tight junction proteins ZO-1 and Claudin-5, indicating compromised barrier integrity. Notably, these deleterious effects—including oxidative stress, mitochondrial damage, and barrier dysfunction—were significantly exacerbated under HG conditions. Collectively, our findings suggest that PVD impairs the vascular endothelial barrier by disrupting eukaryotic iron homeostasis and activating oxidative stress, leading to the downregulation of junctional proteins. This study identifies PVD as a key mediator of vascular injury in DFI and provides a theoretical rationale for targeting iron metabolism and oxidative stress as a therapeutic strategy.